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This invention relates to arresting systems arranged to arrest the travel of aircraft during landing and, more particularly, to arrangements for supporting and lowering a cross-runway cable provided for engagement by the tail hook of an aircraft while landing.
A variety of aircraft arresting systems have been proposed and implemented. Systems particularly suited for arresting of military aircraft equipped with an integral tail hook typically provide a cable stretched across a landing surface for engagement by the tail hook. In some applications a runway is used for both arrested landings and non-arrested landings. For such use, cable support assemblies have been adapted to enable the cable, while stretched across the runway, to be alternatively positioned a few inches above the landing surface or lowered below the landing surface into a slot formed across the runway. When positioned above the runway, the cable is subjected to being run over by the wheels of aircraft and depressed downward. Also, the support members or blocks which position the cable above the landing surface may themselves be impacted by aircraft wheels and provision is typically made to permit the support blocks to be depressed upon impact.
Thus, for a retractable cable system, the support blocks must be implemented in a manner permitting both automated lowering of the cable into a runway slot, and resilient depressing of the support blocks while the cable is in its raised condition, Prior systems have employed cable support assemblies located in enclosures sunk below the landing surface and having covers which are flush with the landing surface and cable support blocks extendable upward through openings in the covers. Arrangements of springs and support block positioning and lowering members of significant complexity have typically been mounted within the enclosures and arranged for remote activation via fluid controlled piston configurations.
FIGS. 1 and 2 illustrate basic components of a previous support block assembly produced by the assignee of the present invention. The components of the assembly are mounted to the sides and base of an enclosure, which is not shown. As represented in FIG. 1, the support arm assembly mounted within the enclosure beneath the landing surface is urged upward by the torsion spring, so as to cause the support block to protrude above the landing surface. The support block is constructed of durable rubber material and has a hole for cable insertion and a cut enabling the cable to be pulled from the support block when hooked by a landing aircraft. When an aircraft wheel strikes the support block, the torsion spring permits the support arm and support block to be depressed downward during passage of the wheel and then returned to the position shown in FIG. 1. FIG. 2 shows the support block lowered for non-arrested landings. Upon activation of the air cylinder the shaft of the piston overcomes the pressure provided by the torsion spring, so as to tilt the support arm downward from horizontal. At the same time, a short control cable is pulled around a pulley and trips a latch arrangement to permit springs to tilt the support block so that an arresting cable held by the support block is lowered into a slot extending across the runway. From the FIG. 2 lowered-cable position, the support block may be returned to its FIG. 1 position by release of piston pressure in the air cylinder, to permit the torsion spring to move the support arm to a horizontal position. At the same time, the support block is returned to its former upright position and latched in place. While the mechanism of FIGS. 1 and 2 continues to provide excellent performance in runway installations, it is desired to provide improved configurations.
Objects of the present invention are, therefore, to provide new and improved hook cable support assemblies and such assemblies having one or more of the following advantages and characteristics:
operating mechanism of support assembly mounted to hinged enclosure cover for ease of servicing and removal;
support arm assembly rotatably mounted to detachable enclosure cover;
all other active components of support assembly mounted to support arm assembly;
control of support block depression during aircraft roll over, by torsion spring carried on enclosure cover;
control of support block tilt for cable raising, by compression spring carried on enclosure cover;
increased time between repairs by use of separately functioning torsion spring and compression spring assemblies; and
long term cost reduction by ease of installation, maintenance, and component and assembly replacement.
In accordance with the invention, a hook cable support assembly, for an aircraft arresting system, comprises the following:
an assembly enclosure having a detachable cover with a pivot structure mounted to the cover;
a support arm supported below the cover by the pivot structure and rotatable about an axis thereof;
a torsion spring device concentric to the pivot axis and arranged to rotate the support arm upward to a static alignment;
a cable support block mounted to the support arm and rotatable between raised and lowered positions;
a four-bar linkage coupled between the support arm and the support block and operable to rotate the support block;
a cylinder/piston device coupled between the support arm and the four-bar linkage and operable on the four-bar linkage to rotate the support block to its lowered position; and
a compression spring device mounted between the support arm and the four-bar linkage and arranged to cause the linkage to rotate the support block to its raised position in the absence of action by the cylinder/piston device to rotate the support block to its lowered position.
Pursuant to the invention, the detachable cover and subsequent components referred to above form an operating mechanism removable from the enclosure by detachment of the cover and associated air supply hose.
For a better understanding of the invention, together with other and further objects, reference is made to the accompanying drawings and the scope of the invention will be pointed out in the accompanying claims.